Revenues Revenues - Significant changes in contract liabilities (Details) $ in Thousands	9 Months Ended
Sep. 26, 2020 USD ($)
Revenues [Abstract]
Revenue recognized that was included in the contract liability balance at beginning of period	$ (9,571)
Increases due to cash received, excluding amounts recognized as revenue during the period	$ 10,479

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130549-203045

Name:	us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration